International Journal of Modern Physics E

This paper examines nucleosynthesis in a low-mass neutron star crust that loses mass due to accretion in a close binary system and reaching a hydrodynamically unstable configuration explodes. The r-process proceeds mainly in the inner crust. Nucleosynthesis in the outer crust is an explosive process with a sharp increase in temperature caused by an outward-propagating shockwave. The number of heavy elements produced in a low-mass neutron star crust during the explosion is approximately 0.041 $M_{\odot }$, which exceeds the number of heavy elements ejected as jets in the neutron star merger scenario.

The results of the study of unstable states in relativistic dissociation of isotopes ${}^{9,7}$Be, ${}^{10}$B, ${}^{12,11,10}$C, ${}^{14}$N and ${}^{16}$O in nuclear emulsion have been summarized. Their decays are identified in distributions by invariant masses determined by fragment emission angles in the velocity conservation approximation. The observed diversity enables us to assume universality in the formation of nuclear-molecular states near the bond thresholds as a consequence of coalescence of emerging $\alpha$-particles and nucleons.

In this work, new vertex detector for the precision registration of D mesons was proposed for MPD experiment at NICA collider. This conception includes three cylindrical inner layers of large area thin (40–50 $\mu$m) silicon pixel sensors, bended around the collider beam pipe and located at a minimum distance from the interaction point of the beams. Also, detailed calculations of identification capability of this vertex detector, within the framework of the decays reconstruction of ${\text{D}}^{+}$ and D⁰ mesons formed in central Au-Au collisions at the NICA collider energies, have been done. Using these estimates of D mesons reconstruction efficiency, the yields of such mesons in MPD experiment were obtained.

The possibilities of using modern ab initio approaches to describe various cluster and decay characteristics of light nuclei and nuclear reactions induced by their collisions, the limits of these possibilities and prospects for expanding these boundaries are discussed. The quality of the description of the spectra of nuclear energy levels, the probabilities of emission of nucleons and clusters by resonant states, the amplitudes of the reduced decay widths of these states and the asymptotic normalization coefficients of bound states are analyzed. It is demonstrated that the results of ab initio calculations of the above characteristics can in many cases be useful for describing and predicting cross-sections for resonant nuclear reactions and analyzing the results of their measurements.

In this paper, we describe an experimental setup designed to investigate double and triple angular correlations, specifically $(n-\gamma )$ and $(n-n^{\prime }\gamma )$-correlations. The experiment was conducted by the TAgged Neutrons and Gamma-RAys (TANGRA) group at the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research. A key feature of this experiment is the implementation of the tagged neutron method, which enables the determination of the emission direction and propagation of neutrons tagged with $\alpha$-particles (${}^4\mathrm{\text{He}}$) resulting from the $T{(D,n)}^4\mathrm{\text{He}}$ reaction. The deuterium–tritium reaction releases approximately 80% of its energy through the emission of 14MeV neutrons. Neutrons scattered by the irradiated target sample were detected using long plastic scintillation detectors, each equipped with fast photomultipliers at both ends. The dual photomultiplier configuration enhanced the position sensitivity of these detectors and improved their angular resolution.

The structure of even-mass isotopes ${}^{70-88}$Ge is described in the framework of the five-dimensional Bohr collective Hamiltonian with the microscopic input from a self-consistent mean-field calculation based on the multidimensional constrained covariant density functional theory. The relativistic functionals PC-PK1 and NL3 supplemented by a finite-range pairing force are used to perform constrained mean-field calculations of potential energy surfaces and collective inertia as functions of quadrupole deformation parameters. Results of calculations manifest the spherical-oblate-prolate shape transition in neutron-rich Ge isotopes. The properties of low-lying collective states are calculated and compared with the available experimental data. In particular, for ${}^{74,76,78,80}$Ge isotopes excitation spectra are accurately reproduced. The results represent a significant advancement in understanding the peculiar structure of the Ge isotopes.

The experiment on photodisintegration of tensor polarized deuteron is in progress. It is carried out at VEPP-3 storage ring using the internal polarized gas target technique. The component $T_{20}$ of the tensor analyzing power is obtained by measuring the target polarization asymmetry in the photon energy range up to 1600MeV. The energy of photons is defined by the system that tags nearly real photons developed at the Budker Institute of Nuclear Physics (BINP).

The neutrino dynamics in hot and dense magnetized matter corresponding to a supernova explosion is considered. It is shown that accounting for fluctuations during interaction of neutrinos with matter leads to the Fokker–Planck equation for the dynamics of the phase space distribution function. The addition to the energy transfer component of the kinetic equation is determined by straggling in neutrino collisions with a magnetized nucleon gas caused by the neutral current Gamow–Teller interaction. When accounting for the effect of fluctuations, the switching of acceleration and stopping regimes in neutrino evolution is evident for average energy. The effect of fluctuations leads to an additional increase in the hardness of the neutrino spectra. It is shown that the high-energy component of the electron antineutrino flux is enhanced in addition due to the effect of neutrino oscillations. Such a strengthening of the spectrum hardness is especially noticeable in the case of the inverted mass ordering and makes the signal more registrable by ground-based detectors. The possibilities of detecting supernova neutrinos by KM3NeT and Baikal-GVD observatories are discussed. The sensitivity of counting rate to the mass ordering is demonstrated to increase at growing difference in the hardness of energy spectra for various flavors.

The small cross-section of the synthesis of the superheavy elements (SHEs) is caused by the hindrance to complete fusion and small survival probability of the compound nucleus against fission. The hindrance to complete fusion is related with such peculiarities of the entrance channel as the mutual orientation angles of the axial symmetry of the colliding deformed nuclei, their mass (charge) asymmetry, the shell effects in their microscopic structure and orbital angular momentum. The appearance of the hindrance to complete fusion has been analyzed in the framework of the dinuclear system (DNS) model by the description of the experimental data obtained in the reactions of the SHE synthesis.

The BM@N is the first experiment at the NICA accelerator complex, which aims to study relativistic heavy ion interactions in the energy region corresponding to high net baryon densities. For the purpose of charged particle identification in the BM@N, two time-of-flight systems TOF400 and TOF700 are used. After the first physics run at the experiment, a series of calibrations have been performed. The calibration methods are described in detail, as well as an estimation of the time and coordinate resolution of the systems.

The emission of spectator neutrons and protons in ultracentral collisions of Bi with the same (Bi) or lighter (W, Cu) target nuclei has been simulated using the Abrasion-Ablation Monte Carlo for Colliders model with MST clustering (AAMCC-MST). It was shown that the detection of forward neutrons and protons in such collisions allows the analysis of the $n∕p$ ratio at the nuclear periphery. The cross-sections to produce a given number of spectator neutrons $N_n$, the average number of spectator neutrons $〈N_n〉$ and protons $〈N_p〉$ in ultracentral collisions were calculated with and without consideration of the neutron skin in Bi. The ratio $〈N_n∕N_p〉$ was found to be particularly sensitive to the presence of neutron skin in Bi–W collisions, providing a potential probe of the enrichment of the nuclear surface by neutrons. However, this sensitivity disappears in Bi–Cu collisions due to the involvement of inner nuclear layers to the spectator emission.

Research into heavy-ion fusion, a key area of modern nuclear reaction physics, has flourished in recent decades pursuant to developments in accelerator technology. The primary goal of studying heavy-ion reactions is to gain knowledge about the underlying processes and how they are affected by entrance channel parameters, such as beam energy, angular momentum and mass asymmetry. The fusion mechanism of non-$\alpha$-cluster projectiles, such ${}^{14}$N and ${}^{19}$F, has been studied in the low-energy zone. It has been challenging to analyze the contributing degrees of freedom in such reactions due to the absence of experimental data. The present study reports the measurement of residual cross-sections from the ${}^{19}$F induced reaction on ${}^{93}$Nb within the energy range of 3–6 MeV/A. The stack foil activation technique followed by offline $\gamma$ spectroscopy was employed to measure the cross-sections of residues populated in the reaction. The experimental data were compared with theoretical predictions from statistical model code PACE4 to probe the underlying reaction dynamics. The imitation of xn and pxn channel data grossly by model code suggests the production of residues via the complete fusion (CF) mode, while the enhancement observation in $\alpha$-channel cross-sections hints at the signatures of incomplete fusion (ICF) in addition to the dominant CF. Thus, the ICF strength fraction ($F_{\mathrm{\text{ICF}}}$) was calculated. Moreover, the estimated incomplete fusion fraction has been used to study the effect of several entrance channel parameters on incomplete fusion reaction dynamics. The present analysis shows the presence of strong clustering in the ${}^{19}$F projectile as $\alpha$ and ${}^{15}$N.

In this paper, we discuss isospin analogues of the tetraneutron resonance and their possible manifestations in nuclear structure and reactions.

High-momentum components of wave functions and two-nucleon short-range correlations (SRC) for the lightest nuclei with $A=3$ are studied within the dibaryon model for $2N$ and $3N$ forces. This model accounts for a possibility of an intermediate six-quark (dibaryon) state formation in the two-nucleon system at short distances. The one- and two-nucleon momentum distributions for ³He and ³H nuclei are compared with those resulting from the widely-used realistic model for nuclear forces. The results obtained are interpreted in view of the recent inclusive $(e,e^{\prime })$ and semi-inclusive $(e,e^{\prime }p)$ experiments.

The antiferromagnetic properties of nuclei are studied within the Wigner function moments method. The solution of the time dependent Hartree–Fock–Bogoliubov equations predicts four low-lying $1^{+}$ states. Three of them are known as various scissors modes. Fourth state is disposed below all scissors modes and represents one of three branches of $2^{+}$ multiplet which can exist in spherical nuclei and which is split in deformed nuclei. It is discovered, that the antiferromagnetic properties of nuclei lead to the splitting of $2^{+}$ states already at the zero deformation. It is shown that the splitting caused by nuclear antiferromagnetism is comparable to the Zeeman splitting in an external uniform magnetic field.

The TANGRA project at the Frank Laboratory of Neutron Physics (FLNP), Joint Institute for Nuclear Research (JINR), Dubna, Russia, aims to investigate the inelastic scattering of 14.1MeV neutrons on atomic nuclei using the Tagged Neutron Method (TNM). As part of this research, we determined the photo-peak efficiencies of HPGe and LaBr₃(Ce) $\gamma$-ray detectors at a new experimental facility. Standard point-like radioactive $\gamma$-ray sources (${}^{22}$Na, ${}^{60}$Co, ${}^{133}$Ba, ${}^{137}$Cs, ${}^{152}$Eu, ${}^{228}$Th) were used for experimental calibration, and GEANT4 Monte Carlo (MC) simulations were employed to estimate full-energy peak (FEP) efficiencies. We accounted for experimental uncertainties in $\gamma$-ray abundance, counting statistics, radioactive source half-life and activity by generating covariance matrices to evaluate detector efficiency. The results showed agreement between MC simulations and experimental data within the limits of experimental uncertainties, demonstrating the reliability of our approach. Our findings align well with those of other studies and MCNP simulations, with improved consistency. This work provides precise efficiency measurements and covariance analysis for HPGe and LaBr₃(Ce) detectors, offering valuable data for $\gamma$-ray spectroscopy applications in nuclear physics, ecology, medicine, geology and archaeology.

After a brief historical background on the first steps and the latest achievements in the study of the electromagnetic properties of neutrinos, the flavor, spin and spin-flavor oscillations of neutrinos in a magnetic field and moving matter are discussed in detail.

In this paper, we present the thermal properties of the medium formed in ultra-relativistic heavy-ion collisions at chemical freeze-out using a thermal model. Experimental data of various hadron species from 0–5% most central Au$+$Au collisions at $\sqrt{s_{NN}}=19.6$GeV from the STAR BES program are used to analyze the thermal properties, namely chemical freeze-out temperature, baryon chemical potential and strangeness chemical potential. A ${\chi }^2$ minimization technique is employed to obtain thermal properties. We also obtain thermal properties with strangeness conversation condition and at zero potentials ${\mu }_B∕T={\mu }_S∕T=0$. We compared particle ratios from the thermal model with the experimental data. The thermal model describes particle ratios within $\pm$2 standard deviations and ${\chi }^2∕\mathrm{\text{NDF}}$ between 1–2. We discuss collision energy dependence of thermodynamic properties of the medium at freeze-out and compare results with the published STAR results and other thermal model calculations.

In relativistic Heavy-Ion Collisions (HIC), scientists have discussed the bottomonium dissociation and survival to gain insights about the characteristics of Quark Gluon Plasma (QGP). The Boltzmann transport equation is commonly employed to explore the interaction between dissociation and recombination rates in QGP, where the processes of formation and dissociation exhibit competing dynamics. However, the Boltzmann equation does not account for the dissociation of new bound states created in QGP medium. To overcome this restriction, a system of independent rates has been developed. This approach assesses the combined effects of gluon-induced dissociation, recombination (although minor for the ϒ states), and color screening on the generation of bottomonium in HIC. The investigation includes PbPb and XeXe collisions at center-of-mass energies $\sqrt{s_{\mathrm{\text{NN}}}}=5.02$TeV and $\sqrt{s_{\mathrm{\text{NN}}}}=5.44$ TeV, respectively. Recombination rates are computed employing the efficient Bateman solution technique, ensuring a comprehensive examination of the interaction between the recombination and dissociation within the QGP, along with the limitations associated with PbPb and XeXe collision kinetics at the Large Hadron Collider (LHC). The model has demonstrated considerable success in accurately describing the suppression of ϒ$(nS)$ states across collision systems of different sizes.

The experimental evaporation residue cross-sections for the reactions ${}^{32}\mathrm{\text{S}}+{}^{182}$W and ${}^{32}\mathrm{\text{S}}+{}^{184}$W show large difference in magnitudes, which is unexpected considering that these reactions only differ by two neutrons. To delve into the dynamics of these reactions, thorough coupled-channels calculations and statistical model calculations were conducted. Notably, the experimental capture cross-sections for both reactions were found to be quite similar and were accurately represented by the coupled-channels calculations. However, a significant discrepancy emerged when examining the experimental evaporation residue cross-sections. In the case of the ${}^{32}\mathrm{\text{S}}+{}^{182}$W reaction, the evaporation residue cross-sections were reasonably consistent with the predictions of the statistical model calculations. On the contrary, calculations for the ${}^{32}\mathrm{\text{S}}+{}^{184}$W reaction not only failed to reproduce the magnitude but also the shape of the observed excitation function. Despite variations in parameters, the statistical model calculations proved inadequate in consistently predicting the evaporation residue cross-sections for the ${}^{32}\mathrm{\text{S}}+{}^{184}$W reaction. This suggests a need for further investigation and refinement of theoretical models to better comprehend the intricate dynamics at play in this specific reaction.

The deformations and the corresponding configurations of the odd-mass Kr, Br, and Rb isotopes are investigated using the adiabatic and configuration-fixed constrained triaxial relativistic mean field theory. Several minima with prominent triaxial deformation and proper configuration are obtained in ${}^{75,77,79,81}$Kr, ${}^{75,77,79,81}$Br, and ${}^{75,79,81,83}$Rb nuclei, indicating the existence of chiral doublet bands. Based on the discussions about the involved orbitals in the chiral configurations, the possible coexistence of chiral and reflection based on the pseudospin orbitals in the ${}^{77,79,81}$Kr, ${}^{77,79}$Br, and ${}^{79,81}$Rb nuclei has been suggested.

The Variable moment of inertia (VMI) model and its extension based on Nuclear Softness (VMINS3) concept with three parameters have been applied to comprehend the systematic of the superdeformed rotational bands (SDRB) in $A\approx 60$–90 lower mass region. The band head spin has been assigned to all superdeformed (SD) bands used in the present manuscript using VMI model and VMINS3 model. The experimental transition energies have been least square fitted to obtain parameters of the model. The variation of the experimental kinematic moment of inertia $J^{(1)}$ and dynamic moment of inertia $J^{(2)}$ against the $N_p{N}_n$ product are examined in $A\approx 60$–90 lower mass region. In addition, the comparison between experimental and calculated $J^{(2)}$ is drawn out against rotational frequency $\hslash \omega$ and the variation of band head moment of inertia $J_0$ with softness parameter $\sigma$ is also examined.

An improved formula including shell closure effects is proposed to investigate $\alpha$-decay half-lives. The coefficients of the improved formula are obtained by fitting the experimental $\alpha$-decay half-lives of 677 nuclei with $62\le Z\le 118$. The root mean square deviation between $\alpha$-decay half-lives calculated by the improved formula and experimental data is reduced from 0.435 to 0.385. The result indicates that the improved formula considering the shell closure effects is reliable in reproducing the experimental $\alpha$-decay half-lives. In addition, the improved formula is extended to predict $\alpha$-decay half-lives of nuclei with $Z=119$, 120 isotopes. The results of the predicted $\alpha$-decay half-lives indicate that $N=184$ appears to be the next magic number beyond $N=126$.

The thermal neutron capture cross-section of ${}^{164}$Dy(n,$\gamma$)${}^{165}$Dy and half-life of ${}^{165}$Dy was determined using Neutron Activation Analysis technique. The Dy target has been irradiated by neutron using Am-Be neutron source at MCNS, MAHE, Manipal, India. Using HPGe detector, the gamma ray spectrum of the irradiated sample has been measured. The half-life of ${}^{165}$Dy was calculated to be $140\pm 1$min. The neutron flux distribution data from the most recent study in Ref. , based on the same Am-Be neutron source facility, have been used to calculate the thermal neutron cross-section of ${}^{165}$Dy. The thermal neutron capture cross-section is determined to be $2008\pm 220$ barns which is in good agreement with the recent measurement in Ref. using neutron diffraction facility.

In this paper, the nuclear structure and some prospective decay properties of the ${}^{128-208}$Sm${}_{62}$ elements are studied. This is accomplished by using an axially deformed oscillator basis and the Relativistic Mean Field model (RMF) with PK1 and NL-SH force parameters. The bulk characteristics are carefully examined, including the binding energy (B.E./A), nuclear radii,quadrupole deformation parameter(${\beta }_2$), two neutron separation energy ($S_{2n}$), and differential change of two neutron separation energy ($d{S}_{2n}$). Estimates are also made for the half-lives of the Sm isotopes for $\alpha$-decay, $\beta$-decay and spontaneous fission (SF). Both our computed Q-values and empirically measurable Q-values are used to determine the $\alpha$-decay half-life periods using the MUDL and AKRE formulae. The results we anticipate could be useful for experiments and future perspective.

In diffractive $p+{}^{16}$O interactions with the subsequent decay of an excited ${}^{16}$O nucleus into proton fragment ($p_f$) and nitrogen nucleus (${}^{15}$N), the kinematical characteristics of $p_f$ and ${}^{15}$N are obtained by the parameter-free Monte Carlo simulation method. The angular, momentum, rapidity and correlation Monte Carlo characteristics for $p_f$ and ${}^{15}$N are consistent with the distributions of the similar quantities obtained experimentally in $p+{}^{16}$O collisions at a momentum of $3.25\mathrm{\text{GeV/c}}$ per nucleon of an incident ${}^{16}$O^∗ nucleus in the rest frame of the target proton (p). The relative probabilities have been found for coherent diffraction ($\sim 59\%$) of a proton (p) on the ${}^{16}$O nucleus as a whole, when an excited oxygen, ${}^{16}$O^∗, nucleus is formed, decaying into ${}^{15}$N and $p_f$ (which is not necessarily the nucleon on which, in fact, the diffraction interaction has occurred), and for incoherent interaction process ($\sim 41\%$) of a proton (p) on one of the nucleons of the ${}^{16}$O nucleus, when this nucleon is observed as a proton ($p_f$) fragment.

In this study, efforts were made to propose a semi-empirical equation for electron capture within the atomic number range $7\le Z\le 103$ and the mass number range of $12\le A\le 252$. About 753 nuclei were considered for the same. These nuclei were categorized into four groups based on the parities of both protons and neutrons: even(Z)–even(N), even(Z)–odd(N), odd(Z)–even(N) and odd(Z)–odd(N). Comparative analysis was carried out between the formula’s predictions and experimental data. The improved semi-empirical formula for electron capture belongs to the first category, requiring only the daughter nucleus’s atomic number and decay energy, making them a valuable tool for predicting electron capture half-lives. The present formula effectively describes even-Z-even-N cases. However, significant discrepancies occur when either Z or N is odd in nuclei, indicating that further refinement is necessary to improve.

The relativistic Hartree–Bogoliubov formalism was employed to explore the role of the nucleon single-particle state in defining the potential energy surface of the ${}^{72}$Kr isotope utilizing density-dependent zero and finite range NN interactions. It is discovered that a significant influence on identifying the ground state minima is the density of states near to the Fermi level.

This paper presents analytical expressions for spectra and wave functions derived from a Davydov–Chaban Hamiltonian, which models the collective motion of nonaxial nuclei within a sextic potential and incorporates the Deformation-Dependent Mass (DDM) formalism. The resulting solution, termed the Sextic and DDM Approach ($\mathrm{\text{Z}}(4)$-SDDMA), is attained through the combined application of Quasi-Exact Solvability (QES) and a Quantum Perturbation Method (QPM). Spectra and $B(E2)$ transition rates are provided for a selection of 15 nuclei: ${}^{\mathrm{\text{122–132}}}$Xe, ${}^{\mathrm{\text{188–198}}}$Pt and ${}^{\mathrm{\text{112–114}}}$Pd, demonstrating a notable agreement with experimental data. Notably, the DDM parameter plays a crucial role in representing, for the first time, the $\gamma$ band levels $6^{+}$ and $7^{+}$ as well as the higher levels within the natural ordering, resolving a previously identified anomaly present in all models related to the Davydov–Chaban Hamiltonian. Additionally, we explore the impact of DDM on the staggering effect of the $\gamma$ band, moments of inertia, and shape phase transition, focusing on the prominent isotopic chains of Xe, Pt and Nd where some of the best candidates are obtained. Moreover, the DDM effect is found to facilitate the emergence of the backbending phenomenon in select nuclei in contrast with other models.

The alpha and cluster decay characteristics of ${}^{299-302}$120 isotopes in the superheavy region are investigated within the Coulomb and Proximity Potential Model (CPPM) framework. The study is significant since several attempts were made during the last one and half decades for the synthesis of Z = 120 isotopes. The alpha decay half-lives are compared with the spontaneous fission half-lives estimated using the formula of Santhosh et al. and identified the isotopes which are stable against spontaneous fission. Possible light cluster emission from the selected isotopes and the branching ratio (BR) are also calculated. Further, heavy cluster emission probability is also studied within the framework of the empirical formula of Prathapan and Biju (PB) and the Modified Balasubramaniam Formula (MBF). We could identify many possible heavy particle emissions with decay half-lives comparable to that of the alpha decay. Experiments can be conducted for the identification of such possible emission fragments. The alpha and cluster decay half-lives are computed using the Universal Decay Law (UDL) and with the Modified Universal Decay Law (MUDL) are also presented for comparison purposes.

The alpha decay half-life and alpha preformation factor in superheavy elements are investigated within the framework of an improved Coulomb and proximity potential model (ICPPM). The CPPM is improved by including a more accurate expression for the diffuseness parameter (b) in the proximity potential. The alpha decay half-lives are calculated by inputting the experimental Q-values and the preformation probability is extracted. It is noteworthy that computed half-lives for alpha decay for superheavy nuclei by using the improved CPPM can accurately replicate experimental data and considerably minimize discrepancies. The estimated alpha decay half-lives are compared with the predictions of the universal decay law (UDL), the Akrawy–Poenaru (AP) formula and the prediction of the modified formula of Santhosh et al. suggested by Luo et al. The hindrance factor (HF) is also calculated for the alpha decays considered in this study. Low values of the HF indicate the high accuracy of the predictions of the ICPPM.